An increasing number of homes with lawns are irrigated with automatic sprinkler systems. These systems consist of a series of subterranean pipes attached to a water source through shutoff valves. The valves are usually connected to an electric timer. A series of sprinkler heads are attached to the pipes and serve to irrigate the lawn and gardens. As the sprinklers are controlled automatically by the electric timer, the sprinkler heads may be broken off or damaged at any time. If the sprinkler system is activated by the timer after the head is broken and no one is around to observe, the sprinkler system can send hundreds of gallons of water out of the broken head before the break is noticed and the system shut down. As a further problem, damage may result to the lawn in hot weather if the system is not run at all while waiting for repair of the broken head. In order to prevent the waste of large quantities of water and to prevent damage to lawns and gardens due to lack of watering, a system is needed that will shut of damaged or missing sprinkler heads while allowing other sprinkler heads attached to the system to remain in operation. A number of devices have been developed to address these problems.
U.S. Pat. No. 4,762,140, issued to Davis, discloses a snap-off plug valve. This device will shut off flow through the line when a downstream emitting element, such as a sprinkler head, is destructively removed from the line. A fracture groove on the exterior of the valve body defines a structurally weakest point and is axially located on the body between an upstream valve seat and a downstream limit stop. The limit stop maintains the valve in an open position during normal operation. Should the downstream emitting element be destructively removed, the supply line will break at its weakest point. The limit stop, being located downstream of the weakest point, will also be removed allowing the valve to close in response to inlet water pressure only, preventing loss of water from the supply line.
U.S. Pat. No. 6,799,732, issued to Sirkin is directed to a water sprinkler head with integral off-on water flow control valve and adaptive fittings therefore. The device in this patent provides a gradual shut off of water at the sprinkler head. The mechanism that shuts off the water to the upper part of the pop-up shaft below where the screen and insert are located is a reverse plunger containing small holes at its perimeter through which water passes from the riser pipe.
U.S. Pat. No. 5,372,306, issued to Yianilos illustrates a fail safe lawn sprinkler device. This device includes a sprinkler head and a valve assembly which couples the sprinkler head to the tap. The valve assembly includes a valve member, a coupling member, and a short nipple. The coupling member is connected to the tap by the nipple and has male threads at its upper end which engage female threads on the sprinkler head.
The valve member is located within a central axial bore of the coupling member and movable axially thereof in a vertical direction between an open or flow permitting position and a closed or flow preventing position. The sprinkler head maintains the valve member in its flow permitting position. However, when the sprinkler head is not in place on the assembly, the valve member is free to move in response to the flow of water through the tap to its flow preventing position, when water under pressure is being supplied to the water supply pipe.
If the sprinkler head is not in place on the tap, the valve member is permitted to move upwardly under the force of water supplied through the water supply pipe to its flow preventing position such that its valve surface engages the valve seat, sealing the outlet through the reduced diameter portion and bore of the coupling member. This shuts off the flow of water through the tap. Thus, the sprinkler head assembly with the valve assembly according to the present invention, permits water to flow out of the tap only when the sprinkler head is in place.
U.S. Patent Application No. 2007/0034712, published for Kah, Jr., disclose a broken sprinkler flow restriction or flow shut off suppressor for sprinkler This device includes a spring loaded restriction valve. The restriction valve may be inserted into the sprinkler body at a threaded inlet portion thereof before the inlet pipe is screwed into the sprinkler body to supply water to the sprinkler That is, the restriction valve is preferably positioned in the threaded area between the sprinkler body and the inlet pipe. The restriction valve preferably includes body portion, a valve member and a spring. Valve body is formed of an annular washer-like plate with one or more downwardly extending ribs. The ribs terminate at their lower ends in a guide ring. The valve member includes a valve disk and a downwardly extending valve stem which is positioned in the guide ring. A peripheral surface of the disk cooperates with a valve seat formed by complimentary surface on the radially inner margin of plate to open and close the valve. The guide ring guides the vertical movement of the valve stem.
The valve remains open unless or until the force of the water flowing through the valve pushes the valve member upward. Spring is partially compressed on assembly and presses against the flange to keep the valve open until the pressure exerted by the flow overcomes the bias of the spring to push the valve member upward into the closed position. This occurs when the pressure of the water flow reaches a predetermined pressure level sufficient to cause a differential pressure across the disk area of valve member to overcome the preload force of spring to keep the valve member down and the flow area between the opening and the disk open. As the valve member moves upward into the closed position, the opening is eliminated and the flow of water is cut off or restricted depending on the diameter fit between the outside circumference of the disk and the opening.
A predetermined pressure at which the valve member is moved into the closed position preferably corresponds to a flow rate in the sprinkler that is likely to cause damage and/or indicate a damaged sprinkler, for example, approximately 5-6 gallons per minute (GPM). The spring may be selected such that the spring bias is overcome at any desired flow rate.
U.S. Pat. No. 4,867,603, issued to Chang is directed to a device for preventing flooding caused by sprinkler failure. This device includes a fitting means which is designed such that its outer diameter fits tightly to the inner diameter of the riser. There is a valve seat affixed to the fitting means. The plug is movable in the axial direction and it is positioned upstream of the valve seat. The spring means provides a mechanical force to keep the plug away from the valve seat under normal flow rates so that the water can flow through the opening between the plug and the valve seat. There is a dashpot means which consists of a cylinder, piston, and piston rod. The cylinder is affixed to the fitting means by the supporting legs. The interior of the cylinder is filled with a viscous fluid and there are narrow flow paths communicating between the two sides of the piston. The piston is attached to the plug. Because the piston must move with the plug, a portion of the fluid in the cylinder is forced to flow from one side of the piston to the other whenever the plug moves. As a consequence the speed of the moving piston is limited by the volumetric rate of flow of the fluid through the narrow flow paths and the flow resistance through the narrow flow paths results in a damping force which resists movement of the plug.
Under normal conditions the water flows from the tee joint, around the plug, and exists through the outlet port. Hydrodynamic drag on the plug arising from the flow tends to drive the plug toward the valve seat. This force, which is approximately proportional to the second power of the flow rate, is transmitted to the spring by the piston and causes a compression of the spring. The spring is so designed that it can support the drag force resulting from normal flow, but not the force arising from flows substantially greater than normal. In the case of a missing sprinkler nozzle, or when the riser is broken, the flow increases substantially, resulting in an even greater increase in the hydraulic drag since the drag increases as the second power of the flow. This increased drag can overcome the spring force and, by pushing the plug towards the outlet port, eventually cause the plug to contact the valve seat. Thus, the flow disclosed shut-off device will remain open and not affect normal operation with intact risers and sprinkler heads, but it will close and shut off the water flow in the event either the sprinkler head is missing or the riser is broken.
It is an objective of the present invention to provide lawn irrigation sprinkler heads that include a self-sealing feature should the head become damaged or destroyed. It is a further objective to provide such sprinkler heads that function to prevent leaks without human interaction. It is a still further objective of the invention to provide sprinkler heads that will permit other sprinkler heads on a circuit to function with the loss of one or more heads on a circuit. It is yet a further objective to provide self-sealing sprinkler heads that are reliable and relatively maintenance free. Finally, it is an objective of the present invention to provide such sprinkler heads that are durable, inexpensive and easily installed.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.